THE IMPACT OF EXTREME HEAT ON PLANTS IN THE GARDEN OR TERRACE

When a heatwave arrives, people are not the only ones who feel it. Plants suffer too. Although many species are prepared to withstand summer conditions, extreme heat can alter their natural rhythm, reduce growth, burn leaves, dry out the substrate and cause stress that is not always visible at first glance.

In gardens and terraces, the problem often becomes more intense. The ground stores heat, walls reflect it, pots overheat and dry air accelerates water loss. That is why a plant that looked perfect in spring can begin to wilt in just a few days when temperatures rise sharply.

What happens to a plant when it gets too hot?

Plants lose water through their leaves through a process called transpiration. This is a natural mechanism that helps them move water and nutrients from the roots to the aerial parts of the plant. The problem appears when the environment is very hot, dry or windy: the plant loses water faster than its roots can absorb it.

When this happens, the plant tries to protect itself. It may partially close its stomata, reduce its activity or temporarily stop growing. This is a survival strategy, but if the heat continues for too long, the damage can become more serious.

Common symptoms of heat stress

One of the first signs is wilting. Many plants lower their leaves during the hottest hours of the day as a defence mechanism. If they recover in the evening, it may simply be a temporary reaction to heat. But if they are still drooping the next morning, they probably need help.

Brown leaf edges, dry spots, shorter-lasting flowers, falling buds, smaller fruits or growth pauses can also appear. In terrace plants, damage can happen more quickly because the roots are enclosed in a pot and exposed to higher temperatures.

Some indoor plants placed outside during summer can also suffer burns within a few hours if they move from filtered light to direct sunlight. That is why it is important to acclimatise them gradually and avoid the harshest hours of sunlight.

Heat does not affect all plants in the same way

Not all plants respond to extreme heat in the same way. Mediterranean species, aromatic plants and those with small, tough or waxy leaves are usually better adapted to sunny and dry environments. On the other hand, plants with large, thin or very tender leaves may lose water more quickly.

Location also matters. The same plant may behave very differently on a south-facing terrace, on a balcony with afternoon sun or in a garden with partial shade. That is why one of the best tips for designing a resilient green space is to apply the idea of “the right plant in the right place”.

During prolonged periods of heat, even established plants can suffer damage. Therefore, it is not enough to think that a resistant plant will never need care. Resistance does not mean a complete absence of maintenance.

How to protect plants during a heatwave

The first step is to reduce stress. It is not advisable to prune, transplant or fertilise during a heatwave unless it is absolutely necessary. Pruning, transplanting and fertilising require extra effort from the plant, and it is better to wait until temperatures drop.

On terraces, moving pots to bright shaded areas can prevent significant damage. If they cannot be moved, temporary shade can be created with shade nets, awnings, reed screens or light structures. The most important thing is to protect plants during the most aggressive hours of sunlight.

It also helps to lift pots away from hot floors, place trays with damp gravel without waterlogging the roots, group plants together to create a cooler microclimate and check watering more frequently. In the garden, mulch protects the soil and reduces evaporation.

Plants better prepared for today’s summers

Extreme heat is forcing us to rethink gardens and terraces. It is no longer just about choosing beautiful plants, but about looking for species capable of better withstanding sunlight, occasional drought and sudden changes in temperature.

Lavender, rosemary, sage, thyme, ornamental grasses, hardy shrubs, adapted perennials and Mediterranean species can be great allies for creating more durable and sustainable outdoor spaces.

At The Original Garden, we believe the garden of the future will be more natural, more efficient and better adapted to the climate. A garden that does not fight against summer, but learns to live with it.

Conclusion

Extreme heat can have a deep impact on plants in the garden or terrace, but it does not have to ruin your green space. Observing symptoms, protecting roots, adjusting watering, creating temporary shade and choosing adapted plants are simple decisions that help keep a garden healthier, more beautiful and more resistant throughout the summer.